People generally prefer daylight over artificial light as their primary source of illumination. Everybody recognizes the importance of daylight in our daily lives. Daylight is known to be important for people's health and well-being.
In general, people spend over 90% of their time indoors, and often away from natural daylight. There is therefore a need for artificial daylight sources that create convincing daylight impressions with artificial light, in environments that lack natural daylight including homes, schools, shops, offices, hospital rooms, and bathrooms.
Artificial daylight sources on the market focus mainly on high intensity, tuneable color temperature, and slow dynamics (day/night rhythms). It is also known to create the appearance of a window in a ceiling facing the sky using a display or foil, for example by displaying a blue sky appearance or the appearance of a cloudy sky.
There has been significant development of lighting systems which try to emulate daylight even more faithfully. For example, such lighting systems are used as artificial skylights, which attempt to emulate natural daylight that would be received through a real skylight. To enhance the realism of the artificial skylight, the skylight solution is usually mounted in a recess in the ceiling, in the same way that a real skylight would be mounted.
One approach which has been proposed previously by the applicant is to create a blue (i.e. clear sky) appearance when looking at a skylight at an angle, for example 40 to 90 degrees, but still emit mainly white light in a beam directed parallel to the normal direction of the skylight surface, i.e. downward. This provides functional white light in a downward direction and more blue light at angles to the normal.
The sides of the recess are by definition located at the edge of the artificial skylight, and they diffusely reflect the light emitted by the skylight under large angles, i.e. blue light for the type of light unit outlined above. Although the intensity of the blue light is typically low, it causes the (typically white) surface of the recess of the skylight to appear bluish or at least very cold white. This does not occur with a real skylight and thus diminishes the effect that is aimed to be achieved with the artificial skylight solution.
The luminance of this reflected light is also rather low, whereas with a real skylight the white wall of a recess would appear very bright, since it is directly next to the skylight.
There is therefore a need for a recessed lighting system which better simulates daylight.